Identifying Gas Transport Mechanisms in Polymer-Grafted Nanoparticle Membranes

Carbon capture and other gas separation processes have become prescient tools in the fight against climate change. Polymer nanocomposites have increasingly replaced distillation columns due to their smaller physical footprint and cheaper operating costs. Polymer-grafted nanoparticles (GNPs) have been investigated in this context to overcome difficulties controlling nanoparticle dispersion. GNP membranes have demonstrated a marked enhancement in gas permeability relative to the neat polymer, with this enhancement greater for larger penetrant sizes. Activation energies of transport display unique trends in grafted polymer systems as a function of penetrant size. Measurements of penetrant sorption indicate larger penetrants preferably transport via lower density interstitial regions between adjacent particles. This work aims to unpack the relationship between transport energies and their associated mechanisms in GNP systems. Changes in preparation methods can affect the underlying structural formation of the disparate polymer chain regions within GNPs. Elucidating the role of the particle surface, dense brush region, and interstitial spaces are all key to an improved mechanistic understanding.